Current regulating system



Jan. 18, 1944..

R. G. THOMPSON CURRENT REGULATING SYSTEM Filed April 17, 1941 5 Sheets-Sheet 1 ifw 9514 6 fw/vaso/v Jan. 18, 1944. R. G. THOMPSON I CURRENT REGULATING SYSTEM Filed April 17, 1941 5 Sheets-Sheet 2 Jan. 18, 1944. R THOMPSON 2,339,526

CURRENT REGULATING SYSTEM s Sheets-Sheet 3 Filed April 17, 1941 311mm FussEL L 6. 7F10MP50- 5 Sheets-Sheet 4 R. G. THOMPSON Filed April 17, 1941 CURRENT REGULATING SYSTEI P m F Jan. 18, 1944.

Jan. 18, 1944. R. e. THOMPSON 2,339,526

CURRENT REGULATING SYSTEM Filed April 17, 1941 5 Sheets Sheet 5 fig- 3 rwvwto'n FussmG T/mMPsa/v Patented Jan. 18, 1944 UNITED STATES PATENT OFFICE CURRENT REGULATING SYSTEM RussellG. Thompson, Elmira, N. Y. Application April 17, 1941, Serial No. 389,034

'16.Claims.' (01. 171-223) This invention relates to electric regulating systems, andmore-particularly tov systems foragainst damage from excessive voltage and current. In the usual form of regulating systems of, this type. electrical contacts are employed which are normally closed to shunt the resistance in the generator field and are opened by electromagnetic devices which are opera (1 when the voltage or current of the generator exceeds predetermined values. The generator voltage and current is quickly reduced by the opening of these contacts which in turn aflect'the electromagnetic devices to again close the contacts. At higher speeds of the vehicle this cycle of operation is repeated at a high rate of speed to provide substantially a vibrating operation of the contacts. j

It is the usual practice to provide a single resistanoe in series with the generator field and to normally shunt this resistance by two sets of normally closed contacts arranged in series. One

set of these contacts is opened by an armature of avoltage magnet whichis attracted when the generator voltage exceeds a predetermined value, and the other set or contacts is opened by an armature oi a current magnet which is attracted whenthe output current of the generator exceeds a predetermined value. Thus, each set of contacts ordinarily operates individually and the opening of either set is effective to provide the full reduction in field current. In order to afin the field current is required, and accordingly speed soon causes the contact surfaces to be coated or pitted and the contacts often stick or weld together thereby causing serious damage to the generator and other electrical equipment, and

frequently destroying the generator, battery, and

1 regulator, in which case the automobile is inoperative.

In view of the above and other considerations, it is an object of the present invention to provide an improved regulating system wherein these difiiculties are overcome by a simple and yet highly effective arrangement wherein either a divided field resistance or a plurality of resistances are employed with a plurality of sets of contacts for shunting different portions of the divided resistance or different combinations of resistances. In this manner the load or the total power to be controlled is distributed or apportioned between the different sets of contacts so that the load controlled by each set of contacts is reduced to a degree which does not cause sufiicient arcing or heating to damage the conulator. i

A further object of the present invention is to provide an improved regulating system of the type described above wherein the load on the ford proper regulation, aconsiderable reduction the opening of either 01' these sets of contacts ordinarily interruptssuflicient current to alone cause considerable damage to the contact surfaces during rapid operation. In addition,'it" will alsobe clear that the abrupt reduction of the field current caused by the opening of these contacts -results in a considerable induced electromotive force in the field windings, and this adds to the damage of the contacts by causing a. considerable areas the contacts open. Thus it has been found that when a-single field resistance is'shunted by such-sets of contacts the opening oi thesecontactscontinuouslyatahighrateof regulator contacts is further reduced by an arrangement of a resistance for dissipating the energy stored in the field upon opening of the regulator contacts, which resitsance is so arranged that current through it does not add to the field current passing through the contacts and thereby further lengthens the effective life of the contacts.

Other objects, purposes and characteristic features of the present invention will appear as the description thereof progresses, during which references will be made to the accompanying drawings', in which:

Fig. 1 is a perspective view showing certain regulating apparatus having one form of mechanical coacting means between the voltage and current relays.

Fig. 2 is a perspective view showing a difierent form of mechanical coacting means between the voltage and current relays.

Rig. 3 is a w: view showing one form of regulating system employing the mechanical coacting means shown in Fig. 1 and shown in connection with a generator for charging a storage battery.

Pig. 4 is a view showing a modishown in Fig. 7. I

ductors could be used. Y

fled arrangement of the regulating system shown in Fig. 3 wherein two sets or contacts are provided on the voltage and current relays and no mechanical coacting means are employed.

Fig. 5 is a diagrammatic view showing another modified form 01' regulating system applied to the battery charging generator shown in Fig. 3 and employing the mechanical coacting means shown in Fig. 1.

Fig. 6 is a diagrammatic view showing still another modified form of regulating system applied to the battery charging generator shown in Fig. 3 and employing the mechanical coacting means shown in Fig. 1 with an additional winding on the voltage relay.

Fig. 7 is a diagrammatic view of a form of regulating system employing the mechanical coacting means shown in Fig. 2 and applied to a battery charging generator of higher capacity.

Fig. 8 is a diagrammatic view showing a modifled form of regulating system also employing the mechanical coacting means shown in Fig. 2 and applied to the battery charging generator Fig. 9 is a diagrammatic view showing a modifled form of the regulating system shown in Fig. 8.

In the drawings, like reference characters refer to the same parts throughout the several views, and in Figs. 3 to 9, inclusive, the apparatus is shown in adiagrammatic' manner to make the invention easily understood, and no attempt has been made to show the particular construction preferably employed in practice.

In Figs. 3 to 6, inclusive, 2. generator of the usual size such as used in pleasure cars and the like is shown conventionally as comprising an' armature IO and field windings II, and in Figs. 7, 8 and 9, a generator of higher capacity such as may be used in commercial vehicles is shown as comprising an armature l2 having two parallel field windings i 3 and I 4. Each of these generators may be driven by the engine of the vehicle such as an automobile, truck, bus, airplane, or the like, or by the axle of a railway car, to generate power for charginga storage battery l5 which may be mounted on the vehicle to supply power for operating lights, fans, radios, air-conditioning apparatus, and other electrical apparatus which may be used on the vehicle. It will also In the illustrated forms or the present regu- 'lating system. .the regulating apparatus includes a voltage relay, a' current relay, and'the usual cut-out or reverse current relay. This cut-outor reverse current relay functions entirely in the usual manner in the presentregulating system,

armature in'its u per or illustrated position wherein a contact 20-on the armature is disengaged from a stationary contact 2|. This armature spring means is adjusted so that when current above a predeterminedvalue flows through the-windings l1 and [8, the armature l3 will be attracted-downwardly to engage contacts 20 and be used in the present regulating system, and

the detail construction of these parts has been shown more particularly to illustrate certain forms of mechanical devices for affording coaction between the voltage and current relays in' accordance with certain forms of the present invention. Accordingly it will be understood that the present invention is not limited to the particulanmechanical details of construction shown in Fig. 1 and Fig. 2 and that various other well known constructions may be used as well.

In Figs. 1 and 2, the voltage and current relays are mounted on a common base 25 which may have flanged-sides (not shown) to house certain resistors used in the system and the cut-out relay may also be mounted on this base. The

general construction of the voltage and current relays may be substantially the same in Fig. 1 and in Fig.- 2 although they are shown as mounted in'reversed relative positions on the base 25 in the two views. The voltage relay comprises a station- -ary yoke 26 of magnetic material with an electromagnet mounted thereon which comprises winding 21 surrounding a central iron core; The yoke 26 and electromagnet are secured to the base 25 but electrically insulated therefrom by the usual arrangement including an insulating plate 28. A

A tractivevarmature 30 is provided to complete the magnetic circuit between the upper end. of

the core of the electromagnet and the upper end of the yoke 26. The armature 30 is provided with a hinge connection to the yoke 26 by a flexible steel strip 3| secured to the lower surface" of the armature and'also secured at-32 to the outwardly bent end of the yoke 26.

steel strip having arms 33 and 34 is also mounted A bifurcated spring at 35 on the armature 30 to move therewith. A

contact 36 is provided at the end of arm 33 which normally engages .a stationary-contact -31 adjustably mounted on an upstanding bracket 38 which is in turn mounted in insulated relation on an extension of the yoke 26.

The end of the spring: arm 34 engages a bendable upward extension 39 of the yoke 26, and the spring tension of the arm thus reacts against this extension to resiliently holdthe armature 30 in its upper position wherein contact 36 engages contact 31. Thus the normal position'oi the armature 30 may be varied by adjusting the staand any well known construction may be used,

means (not shown) which'normally holds the.

tionary contact 31 and the efiectiveforce oi the spring arm .maybe adjusted by bending-the extension 39. In this manner, the voltage relay may be adjusted so that the armature is attracted downwardly towardthe upper end of the core 01 the electromagnet when the current in windings 2'I exceeds a predetermined critical value. It may also be iound'desirable to provide magnetic shunt strips 40 as shown inorderto obtain the desired operating characteristics of the relay.

The mechanical construction of'th'e current relayis generally the same asfthe'voltage relay and comprises a magnetic yoke 42 andelectromagnet having winding 43 of relatively heavy ,wire suryoke 42,

rounding a central iron core and mounted in insulated relation on the base 25 by the plate 28. A tractive ar mature 45 is also provided on the current relay and is hinged by a flexible steel strip 45 secured at 41 to an outward extension oi the A bifurcated spring member having arms 48 and is also secured at 58 to the armsture 45 to move therewith, and the end or the arm'48 is provided with a contact normally engaging a stationary contact 52 adiustably mounted on a bracket 53 secured in insulated relation to an extension oi the yoke 42.

The end or the spring arm 48 'of the current relay also engages a bendable upward extension 54 of the yoke 42 to resiliently hold the armature 45 in its upper position wherein contact 5| engages contact 52. Likewise, the stationary contact 52 may be adjusted to afford slight variation in the normal position oi the armature 45, and the eiiective force or the spring arm 49 may be varied by bending the extension 54 in order that the armature may be attracted downwardly toward the upper. end of thecore oi. the electromagnet when the current in winding 43 exceeds a predetermined critical value.

The mechanical coacting means between the voltage and current relays is arranged in accordvides that when armature 30 of the Voltage relay 'is attracted, contact 36 will be disengagedfrom 'contact3l and the extension 62 will operate on arm 48 to disengage contact 5| from contact 52. Likewise when armature'45 oi the current relay is attracted, contact 5| will be disengaged from contact 52 and the extension 83 will operate on arm 33 to disengage contact 35 from contact 31, Thestationary contacts 31 and 52 may also be adjusted in this form so that both sets of contacts open and close simultaneously upon the attraction of either armature, or they may be adjusted so that the two sets open and close consecutively as will also be discussed later. In some systems, such as shown-in Fig. 7 {or example, insulation may be required between the extensions 82 and 53 and the arms 48 and 33, a

and in these instances'insulatingstrips, such as 59 shown in Fig. 1, maybe provided on the arms 48 and 33.

Inthe various forms of. the present regulating system shown inFigs. 3 to 9, inclusive, the above described apparatusvmay be used, and although the apparatusis shown in a diagrammatic mannor, the same reference characters have been applied to the corresponding parts. Referring to ance with the form shown in Fig. 1 to operate contact 38 as well as contact 5| by movement of armature of the voltage relay but to aiIord operation oi contact 5| only by movement of armature 45 of the current relay. This means is shown as comprising an integral lateral extension Fig. 3, the generator windings comprise a shunt field wherein one end is connected to thelower or terminal of the armature I0 and the otherend'is connected lfy wire 10 through current limiting resistance comprising sections ll and 12 to the, upper or terminal or the 58 on the armature 30 of the voltage relay, and

I the end of this extension overlies the spring arm 48 01 the current relay. The end of the extension 58 may be insulated from the spring arm 48 in some instances by any suitable means such "as a strip 58 of insulating material secured to the.-

upper suriace oi the spring arm. This arrangement then provides that when armature 30 of ,the voltage relay is attracted downwardly, con-- tact 38 will be disengaged from contact 31 and the extension 58 will operate on the spring arm 48 to also disengage .contact 5| from. contact 52.

The stationary contacts 31 and 52 may be ad-' justed so that both sets of contacts open and close simultaneously or they may be adjusted so that the two sets open and close consecutively as will lie-discussed later. It will also be clear that the extension 58 has only a one-way operative connection o! the .armat th the arm 48 so that the attraction e oi the current relay will disengage contact 5| from cbntact 52 without inov-' ing contact as or the voltage relay. Although the relative position of the voltage and current relays is reversed in Fig. 2, the construction thereof may be generally the same as shown in Fig. 1 and the same reference numerals have been applied to the corresponding parts in the two views.-

However the mechanical coacting means'between the voltage and current relays is arranged in accordance with the form shown in Fig. 2 to operate both contacts 38 and 5| by movement of either 1 so that its end portion overlies the spring arm 33.

I'hisarrangementshowninl'ig.2thenproarmature Ill by wire 13. cHowever, at low speeds voltage do not exceed predetermined values, the resistances H and 12 are not eflectiveto limit the current in the shunt field H by reason of shunt circuits around these resistances completed through contacts 5|52 and 36.3l.'"l',n other words, a shunt circuit is completed around the resistance. through wire 14, contacts 52.5|, and wires 15 and 16, and a similar. shunt circuit.

- is completed around resistance 12 through wires 15 and contacts 31-48 and wires 18 'and 19. Under these conditions, iull voltage is'applied to the shunt field II and the armature current or.

the generator flows from the lower terminal of the armature through the ground circuit, wire 80, upward through the lower winding I1 and by ,wire 8| downward through the reversely arrangedwinding l8 Of the cut-out relay, wire 82, winding? 43, and wires 83, "i9 and 13 to the upper terminaloi the armature it). This relative direction of current through the windings i1 and I8 produces a cumulative magnetic flux which attracts the armature l8 to engage contacts 2|) and 2|. The closing or contacts 282| allows battery charging current to flow from the generator through the ground circuit to the battery by'wire and from the battery by wire 88, armature l9, contacts 2|I-2|, downward through winding l8, and back to the upper terminal of the armature In over the circuit previously traced. Thus the battery charging current flows through winding II in the same direction after contacts 2|l- 2| close as in the circuit previously traced with these contacts open, and accordingly the armature 8 is is connected by wires 88, 83,18 and 13 to the 4 upper terminal oi the generator. Thus the currentinthewindlngflisproportionaltothe speed of the generator is increased to a point where this voltage exceeds a predetermined valuea the current in the winding 21 provides sufilcient 2,339,526 output voltage of the armature l0, and when the contacts open is sufficient to seriously damage magnetic force to attract the armature 30 against the force of its spring.

The former the invention illustrated in Fig. 3

" employs the mechanical coacting means between the voltage and current relays shown in Fig. 1,-

and accordingly the attraction or downward movement of the armature 30 not only opens contacts 36-31-but also opens contacts 5l-52 by reason of the extension 58 on armature 30,. Thus,

the attraction or the armature 30 will open the shunt circuit around both of the resistances -1l 2 system.

and 12 so that these resistances will be in series in the energizing circuit of the shunt field II and thereby reduce the current through the field to a value which is efiec'tive to reduce the output voltage of the generator below the safe working voltage for the various parts of the electrical reduces the current in winding '21 to an extent which'releases the armature 30 and again allows the contacts 36-31 and 51-52 to close, and if the'generator is still being operated at a millciently high rate of speed to cause the" output voltageto be excessive, it will be clear that armature 30 will again be attracted to open the shunt circuit around resistances 11 and 12. This cycle of operation of the armature 30 will be repeated as long as the speed of the generator is sufficiently high to tend to.produce an excess volt the contact surfaces and on repeated operation, it has been found that contacts arranged in this manner will stick or weld together and cause damage to the electrical equipment as previously pointed out.

Inasmuch as the load on the regulator contacts is proportional to the value oi'the resistance connected in parallel therewith, it will be clear that the present arrangement greatly reduces the load on the contacts 36-31 and 51-52 by the provision of a divided resistance wherein the sections 1| and 12 are each shunted by an individual set of contacts. Thus, only a portion 1| of the total field current limiting resistance is controlled by the contacts 51-52 and the reage, and the'rate at which this cycle is repeated will increase as the tendency for the voltage f the generator to increase becomes greater to thereby'maintain a substantially constant output voltage of the generator.

It will be clear that thecurrent in the shunt field ll reaches a maximum value just before the contacts 36-31 and. 5l-52 open, and after these contacts have opened this field currmt isreduced to a minimum value. '.This change in current in the field is sufiicie'nt to produce a considerable induced electromotive force, and thisenergy stored This reduced voltag'eoi. the generator may be operated'simultaneously by the armature 30'or one set of contacts may be operated slightly in advance of the operation of the other set. If both sets of contacts operate simultaneously or it no attempt is madeto obtain operation of the two sets at difierent intervals, the two resistances "H and 12 may be of equal values. However, if-

the stationary contacts 3Tand 52 (see Fig. l) are adjusted as previously described so that one set of contacts opens before the other, the resistance associated with the set of contacts which opens first shouldbe a lesser value than the other resistance in order that the loads on the two sets of contacts may be more evenly distributed.

In the present system, the battery 15 may become discharged to such an extent that the in the 'field must be dissipated as the normal I energization' thereof is reduced. For this purpose, a non-inductive resistance 80 is provided for disslpating this field energy as the contacts 36-31 and 51-52 open.

In accordanc with the present invention, this resistance 90 is connected in the circuit so that the normal current passing through it does not pass through the contacts 35-31'and 5l-52 and accordingly does not increase the, load onlthese contacts.- Thus-the resistance 90 is connected as shown so that when the. regular contacts are closed, it is in shunt with the field and when these contacts. open, the resistance 80 is connected around the field through the resistances 1| and 12 in series. In this manner, the resistance 90 is eifectlve to dissipate the energy stored in the field I I in combination with the resistances 1| and 12 and yet the normal current flowing through the resistance 90 from the armature Ill ,does not pass through the-contacts 36-31 and 51-52 as i the case in most regulating systems.

It has been found thatthe combined values of resistances 1| and 12 must be considerable in order -'to sufliciently reduce the generator voltage at high speeds, andwith the ordinary arrangemerit wherein sets of regulator contacts are arrang d in series to shunt aresistance equal tothe combined values ot th present resistances and .1'2, the heatingl'gr arcin when one or these charging current supplied by the generator will become excessive without allowing the output voltage of the generator to reach a value which causes the armature 30 to be attracted. In this instance, this excessive current will cause the armature 45 to be'attracted, thereby opening contacts 51-52 to remove the shunt around the resistance 1| and therebycause a reduction in the field current. In most instances, it has been found that the charging current of the'generator will be reduced sufiiciently to prevent damage by inserting only the resistance 1| in the field circuit, and accordingly, the armature 45 is arranged in Fig. 3 to .operate only contacts 51-52. However, if desired, itwili be clear that the mechanical coacting means between the voltage and current relays shown in ,Fig. 2 could be employed in the system shown in Fig. 3 and in this case, the armature 45 would be provided with exten- $1011 63 (see Fig. 2) whereby attraction of the armature 45 would open contacts 36-31 as well as contacts 51-52 to insert both 0! the resistances 1i and 12-into the field circuit by the operation of the admature 45 alone.

The apparatus used in the modified form of the regulating system shown in Fig. 4 is generally similar to the apparatus previously described inconnectionwith Figs. 1 and 2 with the exception that no mechanicalinterconnection is employed between the voltage and current relays in the form shown in Fig. 4. In this form, a double set of contacts is provided on the voltage relay as well as on the current relay, and each of the twoa ture 30 o! the voltage relay to normallyengage a stationary contact 93, and a second contact 941s also mounted on the armature 30 in insulated relation to the contact 92 by an insulating member 95 and thiscontact 94 normally engages a stationary contact 99. The armature 45 of the current relay isprovided with a contact 91 norin multiple with resistance IIO over a circuit including wires I2I and 1, contacts 31-39 and .wires H8 and H9. In this interval when the contacts "51-52 open and'the contacts 39-31 are still closed, a partial reduction in the field cur- ,rent occurs due to the insertion of resistance in series therewith equal to the total value 01 resistances H0 and III in multiple, which value is mally engaging a stationary contact 99, and a second contact 99 is also provided on the armature 45 which may be electrically joined with the contact 91, and this contact 99 normally engages a stationary contact I00. With this arrange- I ment, the resistance 1| is. normally shunted by a circuit including wire. I 03; contacts 94-99, wire I04, contacts I00-99 and wire I05. Likewise resistance 12 is normally shunted by a circuit including wire I05, contacts 91-99, wire I09, contacts 93-92, and wires I01 and 19.

' v This arrangement shown in Fig. 4 then operates to reduce the generator voltage by removing the shunt around both of the resistances Hand 12 whenever an excessive generator voltage causes armature 30 to be-attracted, or whenever an excessive current causes armature 45 to be attracted. The two sets of contacts associated with each armature may be arranged to open simultaneously or sequentially, and in case they are arranged to open simultaneously the resistances H and 12 may be the same values, but if they are arranged to open sequentially, the resistances asoi'course less than the value or the smaller of the two resistances.

when the contacts 39-31 open upon further movement of armature 30, resistance IIO only is included in the field circuit and accordingly the field current is reduced to a minimum value. In this manner, the arrangement shown in Fig. 5 provides a partial reduction in the field current upon the opening of contacts 5I-52 and a further reduction upon the subsequent opening of contacts 39-31, thereby distributing or apportioning the load between these two sets of contacts.

In the systemshown in Fig. 5, it will be clear that when the output current of the generator becomes excessive without the voltage being sufiiciehtly high to attract armature 30, the armature 45 of the current relay only will be attracted, thereby providing a partial reduction in the field current by establishing the previously traced circuit wherein resistances H0 and III are connected in multiple in the field circuit. However,

' armature 45 could be provided with the extension sociated with the set of contacts which opens first should have a smaller value than the other resistance as explained'in connection with Fig. 3. For example, if the contacts 92-93 are arranged to open before contacts 94-99 and contacts 91-99 are arranged to open before contacts 99- I00, then the resistance 12 should b of less value than the resistance H in order to equalize the load on all the sets of contacts. From the above, I

vention shown in Fig. 4 provides substantially "the same advantages as the form shown in Fig. 3 in that the contact load in controlling the 1 field it will be clear that the form of the present inenergization is distributed between a plurality of sets 01' contacts thereby eliminating undue arcing and heating of the contact surfaces.

In the form of regulating system shown in Fig.

5, the apparatus employed may be the same. as

described in connection with Fig. 3, but the energizing circuit for the field II inFig. 5 includes resistances H0 and III which are arranged in a diflferent manner than the resistances 1| and 12 in Fig. 3. The resistance H0 is connected in the energizing circuit for the field I I'b y wires H3 and H4, but when the output voltage and cur-- rent of. the generator are not excessive, the resistance I I0 is shunted by a circuit including wire II5, contacts 52-5I,- wires H9 and Ill, contacts 31-39 and wires H9 and H9. Under this condition, it will be clear that the resistance H0 is ineflectlve to limit the field current so that full armature voltage is applied thereto.

In Fig. 5, the mechanical-coacting means be 93 shown in Fig. 2 if it is found that a further reduction in the field current is required under this condition. In this case, adjustments could be made so that the attraction of armature 45 only would open contacts 5I-52 and subsequently open contacts 39-31 through the extension 93 thereby reducing the field curent in steps the same as operation of the armature 30 and ding the same distribution of the load between the two-sets of contacts. The regulating system shown in Fig. 6 is generally the same as that shown in Fig. 3 except that an additional winding I25 has been provided on the voltage relay. This winding I25 is shown as connected in series with the shunt circuit around resistance 1 I by wires I29 and I21, and the winding in this instance is so arranged that current in this shunt circuit produces magnetomot ve force opposing the magnetomotive force produced by current in winding 21. The winding 21 maythen have a greater number of ampere turns in Fig. 9 than in Fig.3 soothat normally with contacts 39-31 ,and,5I-52 closed, the efiect of winding I25 will be oflset and armature 30 will be attracted when the generator voltage reaches the same value as in the form shown in Fig. 1.

With this arrangement, it will be clear that when the output current 01' the generator becomes excessive "and the voltage isnot excessive. armature 45 will be attracted to open contacts 5I-52. thereby reducing the field current and interrupting the current in winding I 25. Upon deenergization of winding IN, the full eflect 0f the magnetotween the voltage and current relays shown in Fig, 1 is employed, and in this form it is preferable that the stationary contacts 31 and 52 (see Fig. 1) should be adjusted so that contacts 5I-52 open-first upon attraction of the armature 30 oi the voltage relay. Thus when the generatorvoltage reaches a value which causes attractionjoi motive iorceproduced by the current in winding 21 will beefiective toattract armature 30, thereby causing this armature to be attracted and open contacts 39-31 11' the voltage has not been sufliciently reduced by the opening of contacts 9I-92. The stationary contacts 31 and 52 may also be adjusted in this system so that the attractionoi armature "will open contacts 5I-92 before opening contacts 36-37, thereby deenergizing winding I25 and allowing the full force of winding 21 to be effective to insure quick and positive opening of contacts SIS-31 by the further movement of armature 36.

It will be clear that the winding I25 may be connected into the field circuit in various other ways than shownin Fig. 6. For example, the winding I25 couldbe connected in series with the shunt circuit around resistance I2 and arranged so that its magnetomotive force would add to the magnetomotive force of winding ZI,

in which case the opening of contacts 36-3'I beopened by armature 30 before contacts I-52,

thereby deenergizing winding I25 as contacts 36--3'I open to allow the full efiect of winding 21 to be effective to insure quick and positive opening of contacts 5I52 by the latter part of the movement pf armature 30.

A single shunt field winding is shown on the generator in Figs. 3, 4, 5 and 6, but it is to be understood that the generator field may if desired be divided into a plurality of multiple field windings, each controlled individually by external regulator circuits. Although it is obvious that the regulating apparatu and control circuits shown in Figs. 3 to 6, inclusive, could be duplicated for each of such m'ultiple fields, it is not always necessary to provide all of this additional regulating apparatus for generators having multiple field windings as will appear from the following description of the systems shown in Figs. 7, 8 and 9.

In Fig. '7, the higher capacity generator is indicated as comprising an armature I2 having two parallel field windings I3 and I4 as previously pointed out, and in this system, the field winding I3 is energized by the same general arrangement shown in Fig.3 which includes the current limiting resistances II and 12 with associated contacts 5I-52 and 36-3? on the current and voltage relays. However, these voltage and current relays in Fig. '7 have been shown as provided with themechanical coacting devices shown in Fig. 2 which include armature extensions 62 and 63 which operate contacts 36 and 5|, respectively, through insulating members I29. It will also be noted that a separate voltage relay has been provided in the form shown in Fig. 7 for individually controlling the energization of the other field winding I4. This second voltage relay may be generally of the same construction including a magnetic structure I36 having a winding I3I, one end of which is connected to ground and the other end connected by wires I32, I33, 83, I9 and I3 to the upper terminal of the armature I2. In this manher, the winding I3I is energized in multiple with the Winding 21 of the other voltag relay. An armature I34 on the second voltage relay is arranged in the same manner as the armature 30 and this armature I34 carries a contact I35 which normally engages a stationary contact I35. In addition, an extending end of the armature I34 is operatively connected by an insulating.

assaeae member I38 tooperate a contact I33 which normally engages a stationary contact I46.

A current limiting resistance is included in the energizing circuit for the field winding I4 which is divided into two sections I42 and I43. These two resistances are connected in series with field winding I4 through wires I45, I46, I33, 83, I9 and I3. The contacts I35I36 are then connected around the resistance I43 by wires I48, I49 and I50, and likewise the contacts I39-I4II are connected around. the resistance I42 by wires I5I, I52 and I68.

From the above description of the form of the present invention shown in Fig. 7, it will be clear that the field winding I3 is controlled byv the current and voltage relays to obtain partial regulation of the output voltage of the generator in the same manner as described in connection with Fig. 3 wherein the load is distributed between two sets of contacts 36-3? and 5I-52 to thereby eliminate the damage to the contact surfaces by undue arcing and heating. In this form the output of the generator is further controlled by additional field current limiting resistances I42 and I43 arranged in the energizing circuit of the other field winding I4, and the load in controlling this field winding is also distributed between two sets of contacts I35-I36 and I39-I40; whereby thesame advantages are realized.

It will be clear that an additional current relay could also be added to the form shown in Fig. 7 with its winding in series with the winding 43 of the illustrated current relay, and the armature of this additional current relay could be arranged to directly operate the contact I39 and thereby control the energization of the field winding It in the same manner. that the illustrated current relay controls the energization of the winding I3. However, it is believed that such an additional current relay will not ordinarily be necessary inasmuch as it has been found that a reduction in the field strength provided by the insertion of the resistances II and I2 in field winding I3 will sufiiciently reduce the generator output current to protect the apparatus in instances where the voltage doesnot become sufiicient to attract the armatures 36 and I34 of the voltage relays.

A further simplified regulating system for the higher capacity generator having multiple field windings is shown in Fig. 8. This arrangement employs only one voltage and one current relay as in Fig. 3 and these relays are shown in Fig. 8 as being provided with the mechanical coactin devices 62 and 63 shown in Fig. 2. The field winding I3 in this arrangement is energized over a circuit including wire I55, resistance I56, and

wire I3, but normally the resistance I56 is shunted by a circuit including wire I57, contacts 31- 36, and wires I8 and I9. The field winding I4 is energized over .a similar .circuit including wire I59, resistance I60, and wires I6I and I3, but normally the resistanc I66 is shunted by a circuit including wire I62, contacts 525I, and wire I63.

When the generator voltage becomes excessive in the system shown in Fig. 8, armature 30 is attracted to open contacts 36-31 as wellas con-' tacts 5I-52 through extension 62 to open the shunt circuits around resistances I56 and I and reduce the current in both field windings I3 and I4 to the predetermined low value. These two sets of contacts may be opened simultaneously or sequentially as desired, and it will be clear that the total load in reducing the generator field current is divided between the two sets of contacts so that neither set is overloaded. Likewise when the output current of the generator becomes excessive without an excessive voltage, armature 45 is attracted to open contacts I 52 as well as contacts 36-.31 through extension 53, therebyreducing the field strength in the sam manner.

The regulating systemshown in Fig. 9 is substantially the same as that shown in Fig. 8 except that the voltage relay is provided with the additional winding I 25 shown in Fig. 6. This winding I25 is shown in Fig. 9 as connected inseries with the shunt circuit around resistance The winding 21 may in this arshould be made so that contacts 36-31 open before contacts 5I-52 to deenergize winding I25 and allow the full eflect 0t winding 21 to be effective on armature 30. In this manner, an added force may be applied by armature in. order to insure quick and positive opening of contacts 5I-52.

In the systems shown in Figs. 8 and 9, it will be clear that if the two field windings I3 and II are substantially the same, the resistances I56 and I80 may be equal the current interrupted by contacts 38-3! and 5I-52 will be equal and about one-half the current interrupted by the for controlling the energization of a single field winding. The heat loss at the contacts is proportional to the square of this current and accordingly the present systems reduce the load I or heat loss at the contacts to less than onefourth that in conventional systems now in use. In each or the several diiferent illustrated forms of the present invention, it will be clear that the resistance provided for limiting the field current for purposes of generator regulation is divided into a plurality of sections or separate resistancesquired when a single current limiting resistance is shunted by series contacts on-the voltage and current relays. This is accomplished by connecting one portion of the total current limiting resistance across the contacts of the voltage relay and the other portion across th contacts of the contact as well as the contact of the other relay either simultaneously or sequentially. In the form shown in Fig. 2, this mechanical interconnecting means is eliminated-by a double-set of contacts on boththe voltage and current relays usual regulating systems with a single resistance In this-manner, the ccncurrent relay with interconnecting mechanical means whereby the operation of the armature- -of one of the relays causes operation of its own wherein one set on each relay is arranged in series in a shunt circuit around each section of the divided resistance.

Another feature of the present invention is the provision of the resistance in the circuit so that the energy stored in the generator field is dissipated upon opening of the regulator contacts by this resistance in combination with the other current limiting resistances, and yet the current through this resistance 90 does not add to the current controlled by the regulator contacts. In this manner, the life of the contacts .is further increased by'this reduction in the current which ordinarily passes therethrough.

It is to be understood that various changes may be made in the. specific construction shown, and certain features thereof may be employed without others, Withoutdeparting from the pres- .ent invention as it is defined in th accompanying claims.

The invention claimed is:.

1. In a regulating system for a generator havator, an electromagnetic device responsive to the f current supplied by said generator, a plurality of sets of contacts operated by said electromagnetic devices, and means for varying the energization of said field windings comprising shunt circuits for all of said resistances including a plurality of said sets of contacts all operable by one of said electromagnetic devices and a shunt circuit for one only of said resistances including a set of said contacts operated by at least one of said electromagnetic devices.

2. In a regulatingsystem for a generator having field windings, the combination of circuit means for energizing said field windings including a plurality of resistances, a netic device responsive to the voltage of said genera-tona second electromagnetic device respon sige tothe current supplied by said generator, a plurality of sets or contacts operated by said electromagnetic devices, and means for varying the energization of said field windings .comprising shunt circuits for all or said resistances including a. plurality of said sets of contacts all operable by said first electromagneticdevice and a shunt circuit for one only of said resistances including a set of said contacts operated by said second electromagnetic devices.

, 3. In a regulating system for a generator having shunt field windings, the, combination of circuit means for energizing said field windings including two current limiting resistances, a first electromagnetic device connected'with said generator and having a tractive armature arranged to-operate only when the voltage of the generator exceeds a predetermined value, a second electromagnetic device also connected with said generator and having atractiv armature-arranged to operate only when the output current of the generator exceeds a predetermined value.

a plurality of sets of normally closed contactsarranged to beopened by operation of .the armatures of said electromagnetic devices, and means forvarying the energization of said field windings comprising shunt circuits i'or both of said resistances including two of said sets of-contacts both opened by thearn ature of said first electromagnetic device and a,shunt circuit for one only of said resistances including one'of said sets first electromagoi! contacts opened by the armature or said second electromagnetic device.

4. In a regulating system for a generator having shunt field windings, the combination or circuit means for energizing said field windings including a plurality of current limiting resistances, electromagnetic means connected with said generator and having a tractive armature arranged to be attracted only when the voltage of the generator exceeds a predetermined value, electromagnetic means connected with said generator and having a tractive armature arranged to be attracted only when the current supplied by the generator exceeds a predetermined value, a plurality of sets of normally closed contacts, one so; being arranged to be opened by attraction of the armature 01 either of said electromagnetic means and another set being arranged to be opened by attraction of the armature of one of the electromagnetic means, and means for varying. the energization of said field windings comprising shunt circuits around each of said resistances, each shunt circuit including one of said sets or contacts.

5. In a regulating system for'a generator having shunt field windings, the combination of circuit means for energizing said field windings including a plurality of current limiting resistances, a first electromagnetic means connected with said generator and having a tractive armature arranged to be attracted only when the voltage of the generator exceeds a predetermined value, a second electromagnetic means connected with said generator and having a tractive armature arranged to be attracted only when the current supplied by the generator exceeds a predetermined value, a plurality of sets of normally closed contacts, one set being arranged to be opened by attraction or the armature of either said first or said second electromagnetic means and another set being arranged to be opened by attraction or the armature of said first electro magnetic means, and means-tor varying the enmature of said second electromagnetic means or the armature of said first electromagnetic means and a set of contacts operated only by the armature of said first electromagnetic means, and means for varying the energization of said field windings comprising a shunt circuit around one of said resistances including one of said sets of contacts and a shunt circuit around the other of said resistances including the other of said sets of contacts.

8. In a regulating system for a generator having shunt field windings, the combination of an energizing circuit for said field windings including two current limiting resistances in series and a set of normally closed contacts shunting each of said resistances, an electromagnetic device having an armature responsive to excess voltage of said generator and adapted to open both of said sets of contacts, and an electromagnetic device having an armature responsive to excess current supplied by said generator and adapted to open one of said sets of contacts.

9. In a regulating system for a generator hav- 1 ing shunt field windings, the combination of cirergization of said fieldwindings comprising shunt circuits aroundeach of said resistances,

. eaach shunt circuit including one of said sets of contacts.

6. In a regulating system for a generator having shunt field windings, the combination of an energizing circuit for said field windings including two current limiting resistances in series,- a.

first'electrornagnetic means responsive to excess voltage of said generator, a second electromagnetic. means responsive to excess current sup-.

plied by said generator, contact means including a set 01 contacts operated by either said second electromagnetic means or said first electromagnetic means and a set of contacts operated only by said first electromagnetic means, -and means for varying the energization oi said field windings comprising a shunt circuit around one oi said resistances including one 01'' said sets or contacts and a shunt circuit around the other of said resistancesincluding the other or said sets of contacts.

7. In a regulating system for a generator having shunt field windings, the combination of an energizingcircuit for said field windings including two current limitingresistances in series, a first electromagnetic means having an armature responsive-to. excessvoltage of said generator, a second electromagnetic means having an armature responsive to excess currentsupplied by said generator, contact means includinga set of normally closed contacts operated. by either the arcuit means for energizing said field windings including a plurality of current limiting resistances and a set of normally closed contacts shunting each of said resistances, an electromagnetic device including a winding connected in multiple with said generator and a winding connected in series with the circuit means for energizing said fieldwindings for attracting an armature adapted to open both of said sets of contacts, and an electromagnetic device having an armature responsive to excess current supplied'by-said generator and adapted to open one of said sets of contacts.

10. In a regulating system for a generator having field windings, the combination of circuit means for energizing said field windings including a plurality of current limiting resistances and a 'set oi. normally closed contacts shunting each of said resistances, electromagnetic means having windings connected in multiple withsaid generator and differentially opposed windings connected in series with said circuit means for energizing saidfield, said electromagnetic means being arranged to open all of said sets of contacts, and electromagnetic means having windings in series with the output circuit of said generator and arranged to open one of 'said sets of contacts.

11. In a regulating system for a generator having'a plurality of multiple field windings, the combination of an energizing circuit for each of said multiple field windings including current limiting resistance shunted by normally closed contacts, electromagnetic means having a first armature responsive to the voltage of said generator for opening all of said contacts, and

electromagnetic means having a. second armature operable independently of said first armature in respons to the output current of said generator for also opening all of said contacts.

12. In a regulating system for a generator having a plurality of multiple Jfield windings; the combination of an energizing circuit for one of said field windings including a resistance shunted by normally closed contacts, an energizing circuit for another of said field windings including a resistance shunted by normally closed contacts, electromagnetic means having an armature responsive to the voltage of said generator for opening all of said contacts, and electromagnetic means having an independently 0;

erable armature responsive to the output current of said generator for also opening said contacts.

13. In a regulating system for a generator having a plurality, of field windings, the combination of an energizing circuit for each of said field windings including resistance part of which 'is shunted by one set of normally closed contacts and another part by another set of normally closed contacts, electromagnetic means'for gizing said field windings including a plurality of resistances, each resistance being shunted by two sets of normally closed contacts arranged in series, electromagnetic means responsive. to the voltage. of said generator for opening one of said setsot contacts associated with each of said r'esistances, and electromagnetic means responsive to'the current supplied by said generator for opening the other or said sets of; contact s asso-e ciated with each resistance.

all of 15. In a regulating system for a generator having field windings, circuit means for energizing said field windings including series resistance shunted by a'second resistance in series with a first set of normally closed contacts, a second set of normally closed contacts shuntin said second resistance, electromagnetic means responsive to the voltage of said generator for consecutively opening said second and said first sets of contacts, and electromagnetic means responsive to the current supplied by said generator for opening said second set of contacts.

16. In a regulating system for a generator having a plurality of multiple field windings, the

combination of an energizing. circuit for one of said field windings including a resistance shunted by'a first set of normally closed contacts, an energizing circuit for another of said field windings including a resistance shunted by a second set of normally closed contacts, an electromagnetic device responsive to/excess current supplied bysaid generator for opening said first set or contacts, and an electromagnetic device having an armature arranged to consecutively op n said first and said second sets or contacts and having windings connected in multiple with said generator and difierentially opposed windings connected in series with said first set of contacts in the shunt circuit around the associated resistance.

RUSSELL G. THOMPSON. 

